Endotracheal tubes (ETT) are inserted into a patient's trachea to aid breathing during medical emergencies and in combination with a laryngeal mask are employed during surgical procedures to provide ventilation and to administer anesthesia. It is essential that intubation of the patient be accomplished in as short a time as possible both in a medical emergency and especially during surgery where there is a period where the patient is not breathing due to administration of muscle relaxant.
An ETT 10 is shown in FIG. 1. An ETT comprises a tubular shaft 12 with a distal end 14, a proximal end 15, an inflatable cuff 16 and an inflation lumen 17. During intubation the distal end 14 of the ETT is inserted into a person's mouth and slidably positioned into the person's trachea such that proximal end 15 projects outward from person's mouth. Inflatable cuff 16 is then used to secure the ETT 10 in the trachea. Inflatable cuff 16 is inflated by supplying air at inflation lumen 17. Oxygen and/or anesthetics are then supplied to the person by supplying them utilizing proximal end 15 of ETT.
In order to successfully intubate a patient it is essential that the tube be guided to and through the glottis. Traditionally this is accomplished visually by the operator but in many cases insertion into the glottis difficult to accomplish such as if the operators view is obscured because the patient is improperly positioned or because of anatomic abnormalities or obesity. Various devices such as introducers (introducers) or stylets have been designed as an aid to intubation.
A stylet is a stiff but malleable elongated member inserted into the bore of the ETT to maintain rigidity and to allow the ETT to be shaped so as to aid in the insertion of the ETT into the patients trachea. FIG. 2 is a drawing of a standard stylet 20 and ETT 10 assembly 21 inserted into the trachea 22 of a patient. The ETT 10 is pre-loaded over the stylet 20 before intubation. A distal end 24 of standard stylet 20 is inserted into the ETT 10 while its proximal end 26 extends outward from the proximal end 15 of the ETT 10. Once the assembly is inserted the operator withdraws the stylet 20 through the proximal end of the ETT. Maneuvering of the assembly 21 during the procedure must be done at proximal end 15 of the ETT and proximal end 26 of the stylet 20. This normally requires the operator to change hand positions during a critical stage of the intubation or an assistant since one of the operator's hands are required to support the assembly 21 while the other either holds a laryngoscope or maneuvers the assembly from the proximal ends 15 and 26.
The standard stylet 10, together with the ETT 12 can be bent to form a shape that facilitates insertion into the trachea of a person. Stylets are often made of malleable metals such as stainless steel or copper. They are intentionally designed to withstand much deformation force. Unfortunately this makes the airway vulnerable to injury if the stylets are advanced without being surrounded by an ETT. Keeping the distal tip of the stylet within the ETT and not allowing the tip to extend beyond the ETT's distal tip minimizes the risk of airway trauma from the unyielding stylet. These stylets often even have adapters to hold the ETT in place and prevent the stylet from sliding forward relative to the ETT. Unfortunately, styletted ETTs aren't as maneuverable as thin introducers. When they are covered by an ETT, the ETT can also obscure the view of the airway and glottis from a proximal direction as when using traditional laryngoscopes and newer videoscopes.
As illustrated in FIG. 3 a conventional Eschmann-type introducer 28 is a thin elongated member defining a proximal end 30 and a distal end 32 and that is inserted into the patient's trachea, normally using a laryngoscope (not shown). After the distal end 32 of the introducer 28 has been inserted, the laryngoscope is removed and the ETT is railroaded (advanced) over the introducer 28 from the proximal end 30 and guided by the introducer into the trachea.
The Eschmann-type tracheal tube introducer (formerly known as the gum elastic bougie) is a 60 cm long, 15 French Gauge, flexible device with a coude′ distal tip. During use a curve is also formed towards its distal end. The tracheal tube introducer is used to facilitate difficult intubation. It should not be confused with the more rigid stylet 20 discussed above, which is inserted into the endotracheal tube and used to alter its shape prior to intubation. Unlike the stylet 20 the introducer 28 is inserted independently of the ETT and is used as a guide. Since the introducer is considerably softer, more flexible, and blunter than a stylet, use of an introducer is considered to be a relatively atraumatic procedure compared to a procedure using only a stylet.
FIG. 4 illustrates an intubation in which the introducer 28 has been introduced into the trachea 34 of a patient following which the ETT 30 has been advanced down the introducer and guided thereby into the trachea. After intubation the introducer 28 may be removed or may remain in place if it contains a bore through which fluids may be introduced.
Light guided devices employing transillumination such as ETT stylets, Light wands [e.g., Trachlight™ (Laerdal), Vital Light™ (Vital Signs), Trachlite™ (Rusch), Surch-Lite™ (Aaron Medical Industries, Inc.)] have been used to indirectly indicate entrance into the trachea. These devices also require that the ETT be preloaded and thus do not allow the ETT to be railroaded after tracheal placement of the light wand is confirmed.
To further aid intubation flexible fiber optic bronchoscopes and videoscopes may be provided with an optical function. These devices employ a scope through which the operator can directly view the distal end of the device. These aids are often inadequate in reliably assisting placement of ETTs. A significant challenge when using videoscopes has been guiding the ETT into the trachea. Even though there has been a vast improvement in visualizing the glottis with videoscopes, there have been difficulties noted in guiding the ETT to and through the glottis. For example, with stylet style videoscopes the field of view may be obscured by the large diameter of the ETT. Also since the stylet style videoscope is surrounded by the ETT some maneuvering is impossible. An additional problem with devices containing optics is that bending of the device in certain regions, especially at the distal tip cannot be accomplished because this is where the optical component is located.
In an attempt to overcome some of the deficiencies of stylet style videoscope devices the stylet can be provided with an extendible member telescopingly disposed within the body of the stylet. For example Patent Application Publication 2008/0017195 describes an extendable lighted stylet that is inserted into the bore of an ETT. The stylet contains an extendable member that carries a light source which can be extended using a handle portion at its proximal end. The field of view can be obscured by the larger diameter ETT and operation of the stylet requires the operator to use one hand at the proximal end while supporting the tube and stylet with the other hand. This is difficult if a laryngoscope is also being utilized and in fact may require two people to successfully perform the intubation. In addition bending the device to aid intubation can be hampered by the optical components.
A similar system is described by Rayburn et al. in U.S. Pat. No. 5,733,242. A stylet with a scope tube contains a light transmitting optic fiber. The stylet is disposed in the bore of an ETT. The scope tube can be used to guide an ETT. This device is subject to the same problems described above, especially as operation must be accomplished at the proximal end handle portion.
Rigid stylets have also been used in combination with conventional laryngoscopes for intubations to provide an enhanced view of the glottis during the procedure. However it has been well documented that providing a good view of the glottis does not always correlate with successful airway intubation. The limitations of video laryngoscopes in advancing the ETT through the vocal cords and into the glottis have been well described.1,2 Using a stylet to curve the ETT through the vocal cords and into the trachea has often proven difficult due to, among other things, having the bevel of the ETT become stuck at the arytenoids, or impact the anterior wall of the larynx. In addition the discomfort to the patient may be increased. The use of a softer stylet has been suggested to allow for the adjustment of the ETT and result in faster intubation times.31 Doyle D J, Zura A, Ramachandran M, Videolayngoscopy in the management of the difficult airway (Letter). Can J Anesth 2004; 51:952 Cooper R M, Videolarynoscopy in the management of the difficult airway (Letter, reply) Can J Anesth 2004; 51: 95-63 Rai M R, Deering A, Verglose C, The Glidescope system: a clinical assessment of performance. Anesth 2005; 60:60-4
Stylets require that the ETT be loaded over the stylet. A problem with the preloaded-ETT-over-the-stylet designs is that they often require use of a control mechanism located at the proximal end. This can be far behind the operator's supporting hand. The operator's other hand must continue to hold the videoscope in a fixed position, so maneuvering from the proximal end of the ETT requires distracting maneuvers by the operator or the help of additional personnel trained in the use of the device. Also, the larger diameter ETT can interfere with operator's line of sight during intubation.
The Eschmann-type introducer has been successfully used for numerous difficult intubations in combination with traditional laryngoscopes. The introducer permits one hand operation from a medial portion of the device making it easier to maneuver the distal end during difficult intubations. Some difficulties have been noted when the introducer is used in combination with the more recently developed videoscopes. Unfortunately, intubating-introducers such as the Eschmann introducer weren't originally conceived of for use with videoscopes. Videoscopes have created the need for more dynamically shapeable designs to adjust to the unique angles of approach required when viewing the glottis through the videoscope. For example, a good view can often be obtained and an introducer can be advanced close to the glottis, but there may be difficulty advancing the tip of the introducer through the glottis. Often the tip of the introducer can be seen with the glottis clearly in the background, but the distal tip of the introducer can't be advanced through the glottis. This often occurs because the introducer must be pre-bent to align with the glottis but can't be extended distally in the direction toward which the distal tip points
In an effort to alleviate this problem some manufacturers have inserted a flexible wire into the introducer to provide for improved molding of the introducer so that the distal end portion can point towards the glottis. But there is no provision for advancing the distal tip toward and through the glottis. Even with the proximal portion of a telescoping device pointing in the general direction of the glottis, maneuvering is still needed to actually advance the distal portion through the glottis.
Yoshida et al. (US Patent Application Publication US2008/0017195, Jan. 24, 2008) teaches a stylet that includes an extendable member carrying a light at its distal tip. This device is subject to many of the disadvantages described above and in addition includes a handle portion at the proximal end that requires the ETT be preloaded over the stylet. Manipulation is by the handle portion at the proximal end and cannot be maneuvered using one hand.
It would be desirable to have an introducer that does not require preloading of the ETT and that does not obscure the view through a videoscope. In addition it would be desirable to have an introducer readily moldable into a desired shape and that has a maneuverable extendable member that can be readily inserted into the trachea using one hand and that can be supported and controlled at a point medial the distal and proximal ends of the introducer.